Standard keyboards for typewriters and computers have four parallel rows of keys: one numeric and three alphabetical. The rows are placed one on top of the other, but are staggered somewhat in order to shorten the finger-travel distance, or "throw", between keys in adjacent rows. Minimizing this distance is important, because the farther a finger must be thrown from its normal, or "home", position, the greater the chance for making a typing mistake. Furthermore, longer strokes require more muscle effort to execute, and thereby increase operator fatigue.
This parallel arrangement of straight rows of keys requires that the hands be held in a relatively unnatural position, namely, with the wrists held close together and the hands turned outward. At best, this position causes fatigue and strain -- at worst, it may be associated with progressive deterioration and injury, such as carpal tunnel syndrome, which has been found to be increasing concomitantly with the increased used of computer and word processor keyboards.
Bending the rows of keys in the middle to form a V-shaped arrangement is known, although not widely adopted. This arrangement can allow the operator to turn his or her wrists outward somewhat so that the hands are held more directly in line with the forearms -- a less fatiguing and safer arrangement.
Since the V-shaped rows are stacked one upon the other, such a keyboard, as a whole, may more properly be termed "chevron-shaped"(a chevron being a four-sided solid having a V-shaped top and a V-shaped bottom offset parallel to the top). However, these terms will be used more or less interchangeably herein, except where an explicit distinction must be made.
A problem with existing chevron keyboards is that they do not utilize the universally standard key arrangement known as the QWERTY keyboard. "QWERTY" stands for the names of the keys occupying the left side of the upper row of alphabetical keys. Therefore, existing chevron arrangements must be relearned by a typist whose only prior training and experience is on QWERTY keyboards. Furthermore, many chevron keyboards have such large gaps between the keys on alternate sides of the keyboard that they could not be readily modified for use by a QWERTY typist. They also would not be suitable for use in a keyboard wherein it is desired to minimize the typing area. This is the case, for example, with laptop, notebook and pocket computers.
Prior developments in this field may be generally illustrated by reference to the following patents:
______________________________________ Patent No. Patentee Issue Date ______________________________________ 2,725,677 WG A. Muther Dec. 22, 1977 2,122,947 GB W. Hawkins Jan. 25, 1984 4,579,470 C. Casey Apr. 01, 1986 4,824,268 H. Diernisse Apr. 25, 1989 4,655,621 R. Holden Apr. 07, 1987 332,476 GB K. Marloth Jul. 24, 1930 2,218,065 WG G. Nawroth Oct. 31, 1973 556,422 A. Von Kunowski Mar. 17, 1896 2,318,519 C. C. M. Palanque May 04, 1943 4,483,634 W. U. Frey et al. Nov. 20, 1984 4,597,681 A. N. Hodges Jul. 01, 1986 4,737,040 T. Y. Moon Apr. 12, 1988 552,611 WG G. Vollberg Jun. 15, 1952 2,122,947A GB W. R. Hawkins Jun. 25, 1984 4,814,747 J. D. Wathor Mar. 21, 1989 4,739,316 S. Yamaguchi et al. Apr. 19, 1988 4,476,462 A. P. Feldman Oct. 09, 1984 4,808,017 H. F. Sherman et al. Feb. 28, 1989 4,633,227 W. A. Menn Dec. 30, 1986 ______________________________________
Patent WG 2,725,677 to Muther teaches a chevron keyboard where the space between the main key rows is filled with additional keys. However, the rows are not staggered and the key shapes are not altered to provide an interlocking fit.
Patent GB 2,122,947 to Hawkins teaches a thumb key whose shape is modified into that of a diamond so as to fit into the space between the key rows of a chevron keyboard.
U.S. Pat. Nos. 4,579,470 to Casey and 4,824,268 to Diernisse teach keyboards having something of a "V" shape and staggered keys. While the 3 470 patent shows one triangular key in the center, none of the keys are themselves chevrons, and the rows do not actually interlock.
The Frey patent, U.S. Pat. No. 4,483,634, is for a keyboard arrangement where a central keyboard is arranged in a V-shape. There is an unused triangular region in the center of the typewriter area. The keyboard also has a smaller keyboard on both the right and the left hand sides of the central keyboard. The rows are not unbroken "V"s. Two keys are chevron-shaped but are rotated 90 degrees. Thus, they extend from the bottom row up into the next row and do not facilitate the interlocking of rows.
The Hodges patent, U.S. Pat. No. 4,597,681, is for an adjustable keyboard wherein a standard keyboard is divided in half and each half can pivot around a pin such that the keyboard may be arranged on an angle in a V-shape. However, the rows break open upon pivoting. A tab key is chevron shaped, but also extends from one row up into the next row and does not facilitate the interlocking of rows.
The Palanque (U.S. Pat. No. 2,318,519), Hawkins (Great Britain No. 2,122,947A), and Vollberg (West German No. 552,611) patents also show keyboards where the keys are positioned on an angle to form a V-shape. However, the rows are broken by an unused, approximately triangular shaped region in the center of the keyboard, from which the keys radiate upward.
Not only does breaking of the rows prevent the effective staggering needed to shorten finger throw distance, it wastes space -- in an age where smaller and smaller keyboards are being demanded.
The rest of the patents are representative of what is in the art.